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EQ Adjustments >500 Hz not recognized in REW SPL Graphs?

2981 Views 16 Replies 4 Participants Last post by  Mr. Neverbicker
Here's the sequence of my setup...

=> REW Test Tone
=> Asus Xonar HDAV1.3 Deluxe Sound Card (7.1 Analog Out)
=> 7.1 Amps & Speakers
=> Berhginger ECM8000 Mic (With Downloaded Calibration File)
=> Nady SMPS-1X (XLR Phantom Power Supply)
=> Samson S-Convert (Balanced XLR to RCA Converter)
=> Asus Xonar HDAV1.3 Deluxe Sound Card (Preamp Mic Input - Calibrated)
=> REW Measurements (C Weighted Off)

When I adjust the EQ settings for the Asus Xonar Sound Card Analog Outputs, the changes are not reflected in the REW measurements for any frequency above roughly 500 Hz. For instance I can adjust 8 KHz from min to max, and I hear the SPL difference in the sweep tone, but the frequency SPL graph is still identical. It's a an upward curve from 500 Hz to 20 KHz, and I can't get it to change no matter how I set the EQ. But then if I adjust 120 Hz, I hear the difference in the sweep tone and it's directly reflected in the graph. I can swing the EQ settings all over the board, but above 500 Hz the graphs continue to overlay almost perfectly.

Is there a software setting I'm not using correctly?
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,,,,snip,,,,It's a an upward curve from 500 Hz to 20 KHz, and I can't get it to change no matter how I set the EQ. But then if I adjust 120 Hz, I hear the difference in the sweep tone and it's directly reflected in the graph. I can swing the EQ settings all over the board, but above 500 Hz the graphs continue to overlay almost perfectly.

Is there a software setting I'm not using correctly?
- My WAG guess is that you have setup a feedback loop in your soundcard somewhere / creating a distorted snap-shot of the sweep .
- A feedback loop will mask most changes made to EQ .

- You need to get into your soundcards bundled software and turn off "Input Monitoring" ( or something named similarly ) if you find it is on .

- Mind you , a feedback loop should have shown up when you calibrated the soundcard ( as the inability to get stable levels ) .

<> EarlK
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One Type of Routine ; To See if You Have Choosen To Make A Feedback Loop .

> Run another SoundCard Calibration routine but without using the loopback cabling .

> If there's no FeedBack Loop setup it should look like this when you test levels ;



> If there is a FeedBack Loop present , it'll look something like this ( when you test levels ) ;
- In this case , I have created the feedback loop internally to the computer by choosing as my input , Stereo Mix" .




<> EarlK
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Re-checked the settings, did the test for any feedback loops and it checks out ok. Check out the SPL Graph. I can fine tune everything to the left of 1 KHz, but not to the right. It just ramps up. However, if I make extreme EQ adjustments above 1 KHz, minor differences are reflected in the curve. For instance if I EQ out all of the upper frequencies, the upward curve reduces somewhat, yet I hear no upper frequencies coming out of the speakers and it sounds worse than a cheap alarm clock radio. I left the calibration curves in the graphs in case they are helpful.

Text White Line Pattern Plot


Also, when I'm taking measurements, I get a warning for very low signal level, but I wonder if this is because the mic is only recording on the left channel and not the right?

Here's the rest of the graphs. In the last three, something begins to happen above 1 KHz:

Green Text Blue Plot Slope


Green Text Plot Slope Line


Text Line Plot Font Pattern


Text Line Design Parallel Pattern


Text Plot Line


Text Plot Line Slope Parallel


Colorfulness Line Rectangle Plot Graphic design


These are through all 5 channels, no sub. Overall I very impressed with how it sounds, as long as I use default EQ for upper frequencies and ignore the graphs. Any glaring issues?
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Well, I don't see any "Smoking Gun" in any of the pics you posted .

I do see that your sweeps are being contaminated by some UHF content that is Prefade the onboard ( soundcard ) EQ .

I'm clueless as to what would be the cause ( if it's not a feedback loop of some sort ) .
- BTW ; Reverb is created using feedback loops via multiple taps of the original sound .

If you can't find a way to fix this contamination / I would suggest simply using another sound card for measurements ( employing the KISS approach ) .
- A Behringer UCA202 with a RadioShack SPL meter works for just about everyone (good up to 2 or 3K ).

- That's all I got <<< EarlK
Thanks. I'm thinking it's something along the chain of components of the mic input, the phantom power injector or the XLR to RCA converter box. I think something there is not happy. Is there an external sound card with XLR mic input with internal amp mic and Phantom power for the ECM8000?

I'm looking at the Shure X2u. Pretty nifty.
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Is there an external sound card with XLR mic input with internal amp mic and Phantom power for the ECM8000?

- The following is the setup that I recommend the most frequently ( except, using the Behringer UCA202 instead of the built-in soundcard ), because it follows the KISS protocol .

- That UCA202 usb soundcard uses the built-in SoundCard drivers for the PC ( & the Mac ) . This fact alone will save everyone a lot of head-aches .



- The next up in complexity is this ( but only barely ) ;
- If you want an outboard PreAmp , this is what I recommend you emulate . The Xenyx 502 has phantom power, so that's the cheapest choice .



- The setup that trips up most of the people logging onto this forum is the following ;



- As a consequence, I won't make SoundCard recommendations that support this setup, since it'll invariably come back to bite me ( you know where ) .

- Therefore ( if this is the way you want to go ), you're on your own to research a soundcard that plays nice with your computer type, your Operating System, and to find one that doesn't overly tax your skill set at getting a handle on whatever built-in features it has that might be attracting you .
- I'll leave it to others here to make recommendations along this line .
- One note ; unless you have a PHD in digital plumbing , avoid Emu's offerings ( since PatchMix is guaranteed to trip-up the casual user ) .

cheers <> EarlK
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The Behringer UCA202 doesn't seem to support XLR nor Phantom power. The Xenyx 802 looks like a steal for what you get, but I'd really like to bypass my current sound card's line in, just in case the problem is there; so I think I'll try the Shure X2u. Seems like an all-in-one solution that eliminates all of the additional components that might be causing the issue here.

Re-checked the settings, did the test for any feedback loops and it checks out ok. Check out the SPL Graph.

For starters, your signal is way too low. Get it up out of the room’s ambient noise floor! There’s a reason we recommend calibrating at 75 dB. :)

That said, I agree that the problem might be somewhere in all that stuff you have in the signal chain. Hard to say.


The Behringer UCA202 doesn't seem to support XLR nor Phantom power. The Xenyx 802 looks like a steal for what you get, but I'd really like to bypass my current sound card's line in, just in case the problem is there; so I think I'll try the Shure X2u. Seems like an all-in-one solution that eliminates all of the additional components that might be causing the issue here.
You wouldn’t need the UCA202. It’s just a sound card, and you already have one. The X2u might be good for troubleshooting purposes, but not for taking measurements. The problem with those USB mic adapters is that you can’t calibrate them. So for instance, if its response drops like a brick below 100 Hz, that’s what your graph is going to look like.

Regards,
Wayne
I had it ear pearcing loud. I had to cover my ears to take measurements. Definitely well beyond 75 db. Now that I think about it, the sound card's mic input works because I was able to calibrate it without a hitch. As you can see in the SPL graph, it's 75 db on the mark. Yet when I plug in the XLR/RCA Converter -> Phantom Power Injector -> Mic, 75 db just can't be had no matter how loud I take measurements. I maxed out the mic input level and enabled mic boost for the sound card. Neither of those needed to be done to get 75 db during calibration using the same mic input.

I'll give the Xenyx 802 a shot. I can calibrate with it in the loop.
Looks to me more like the wrong channel is selected and you are measuring the cross talk pickup rather than the direct mic signal on the other channel.
Thanks John. That was part of the problem. I just switched the mic from the left channel mic input to the right channel mic input, and the measurements were the same. So then I used an RCA "Y" from the mic to both the left channel mic input and the right channel mic input and measured using the same output power I had been using. The first measurement averaged 130 db. So that explains the ear piercing sweeps that scared my kids at the other end of the house!

Maybe it was difficult to diagnose because not many sounds card have two mic inputs? Anyhow, I won't have time to do some real tests now, but I definitely look forward to finishing this up hopefully tomorrow afternoon.
Here's the sequence of my setup...

=> REW Test Tone
=> Asus Xonar HDAV1.3 Deluxe Sound Card (7.1 Analog Out)
=> 7.1 Amps & Speakers
=> Berhginger ECM8000 Mic (With Downloaded Calibration File)
=> Nady SMPS-1X (XLR Phantom Power Supply)
=> Samson S-Convert (Balanced XLR to RCA Converter)

=> Asus Xonar HDAV1.3 Deluxe Sound Card (Preamp Mic Input - Calibrated)
=> REW Measurements (C Weighted Off)
- The red highlighted items are not mic pre-amps and therefore don't offer any gain .

- Based on your most recent comments, your problem appears to be one of pre-amp gain ( ie; you don't have enough available from the computers inboard soundcard ) .

- I standby my advice about recommending a Xenyx 502 mixer , as well as a UCA202 - usb ( linelevel ) soundcard .

- From a trouble-shooting POV this is the best way to go ( mostly for those trying to help-out a noob ) .

- I feel quite comfortable asking the less skilled to ante-up a few more bucks to streamline the "Please HelpMe !" process, when the poster is reaping the benefit of a free program that should cost anywhere between $ 300 to $ 1000.00 .

cheers <> EarlK

PS ;Hopefully this is close to being sorted / as I'm now out of town till Friday .
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It's sorted out. Read my previous post. Thanks.
I finished a new round of measurements and adjustments, and now I'm a believer. I tried making EQ adjustments by ear before, and it's just not the same as a real calibration. It has really opened up the sound, much more dynamic and real. I utilized all of Ethan Weiner's instructions for room treatment and now that it's calibrated, the sound is truly incredible.

Thanks to everyone who brought REW!
Seriously?? I'm a programmer by trade, and I know the amount of dedication and sacrifice it takes to complete such a project. This program is very well done. I think that to myself every time I open it up and use it. It's very intuitive. It's just so easy to pop it up, plug in the mic, take measurments and make adjustments.

On a side note, the improvement I've experienced with calibration is *far* greater that the differences among hi-fi speakers I've heard. I can't imagine why hi-fi store demo speakers without calibration within the demo room, yet I know most don't because almost all of the demo installs I've seen don't have much even in the way of EQ. Most hook up a $10k+ cd/preamp/amp combo directly to a $10k+ pair of speakers. I don't feel you can give a speaker any justice without a calibration.

Anyway, this is a really great program! I will remember this "John M".
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